This invention relates to a soft finishing agent, and, more particularly, to a soft finishing agent which is capable of providing fibers with an excellent flexibility, and antistatic and water adsorption properties. 2. Description of the Background
Cloth becomes hardened and loses its pleasant softness, as it is repeatedly worn and washed, due to the loss of fiber treatment agents through washing or to deterioration of the fibers themselves. Because of this, the tendency has increased in recent years among quite a few families to use more and more soft finishing agents which can reinduce the flexibility and antistatic property into fibers.
Most of the soft finishing agents for household use currently on the market are those containing, as a major component, a cationic active agent having one or two long-chained alkyl groups in a molecule, and specifically, among other things, di(hydrogenerated tallow oil-derived alkyl) dimethylammonium salt.
This quaternary ammonium salt, when used even in a small amount, can provide various fibers with good flexibility and antistatic effects. This flexibility is exhibited by a reduced friction coefficient on the fiber surface, which is caused by a lubrication effect of the hydrophobic part of the substrate compound molecule, the quaternary ammonium salt, absorbed onto the fiber surface. Therefore, the hydrophobic characteristic is considered to be essential for a soft finishing agent to be capable of providing an excellent softening effect. Ths hydrophobic characteristic, however, causes cloth to become water repellent and decreases its water adsorption capability. The decrease in water adsorption capability is particularly remarkable when the soft finishing agent is used at a high concentration.
In view of this situation, a number of studies have been conducted to promote the water adsorption capability of soft finishing agents. Thus, the use of a branched alkyltype quaternary ammonium salt (U.S. Pat. No. 3,377,382 and U.S. Pat. No. 3,395,100), and an imidazolinium compound derived from oleic acid (J. American Oil Chemical Society, 61, 367, (1984)], have, heretofore, been reported.
These compounds exhibit a sufficient effect concerning water adsorption. Their softening capability, however, is clearly inferior to that of the above-mentioned di(hydrogenated tallow oil-derived alkyl) dimethylammonium salt. In order to supplement this insufficient softening capability, the imidazolinium compound is conventionally used together with di(hydrogenated tallow oil-derived alkyl) dimethylammonium chloride, an imidazolinium compound derived from hydrogenated tallow oil, or the like. Inclusion of these compounds, however, brings about insufficent water adsorption capability. In the case of the above-mentioned .alpha.- or .beta.-branched alkyl-type quaternary ammonium salt, use of linear alkyl-type quaternary ammonium salt in conjunction with the .alpha.- or .beta.-branched alkyl-type quaternary ammonium salt, is proposed [Japanese Patent Laid-open Nos. 69998/1974, 53694/1975, 144174/1973, U.S. Pat. No. 3,892,669, and German Pat. No. 2,625,945]. These products are insufficient in their softening capability, however, and none of them has been successful in providing a completely satisfying soft finishing agent.
In view of this situation, the present inventors have undertaken extensive studies for the purpose of developing a soft finishing agent which can provide a satisfactory softening capability and a good antistatic effect, without impairing the water absorption or retention capability of the treated cloth. As a result, the inventors have found that certain di-long-chained quaternary ammonium salts having specific characteristics can satisfy this requirement. This finishing has led to the completion of this invention.